Process for the production of metal electrodeposits



United PROCESS FOR THE PRODUCTION OF IVIETAL ELECTRODEPOSITS Wennemar Strauss and Wolf-Dieter Willmund, Dusseldorf-Holthausen, Germany, assignors to Dehydag,

Deutsche Hydrierwerke G.m.b.H., Dusseldorf, Ger-' many, a corporation of Germany No Drawing. Filed Feb. 12, 1958, Ser. No. 714,687

Claims priority, application Germany Feb. 13, 1957 11 Claims. (Cl. 204-46) This invention relates to a process for producing metal Patent F 2,986,498 Patented May .30, 1961 4 if tached either on the X or R groups, and may be provided,

N-ethyl-N-fi-aminoethyl-aminoethane-sulfonic acid electrodeposits, and more particularly to additives for electroplating baths which are capable of eliminating the adverse efiects of impurities in such baths upon the quality of the metal deposits produced by means of such baths.

It is well known in the electroplating art that inorganic 3 impurities occurring in electroplating baths oftenhave an adverse effect upon the metal deposits obtained therefrom, particularly if such baths contain brightening agents. Impurities which adversely affect the qualities of metal electrodeposits include those which cause the 1 hardness of tap water as well as those contained in technically pure metal salts usually employed to make up the electroplating solution. The adverse effect of these impurities is particularly noticeable in electroplating processes for depositiing copper on metal objects, and

in electroplating with sulfonic acid brightening. agents. It is an object of the present invention to provide a method of modifying electroplating baths with additives baths on the brightness of the metal electrodeposited therefrom.

Other objects and advantages will become apparent as the description of our invention proceeds j We have found and have described in our copending application Ser. No. 458,984, now abandoned, that the adverse eflect of inorganic impurities in .electroplating baths upon the qualities of electrodeposits produced from such baths can be eliminated by adding small amounts of amino compounds free from carboxyl groups to the electroplating baths. in accordance with our prior application have the general structural formula wherein R R R and R are hydrogen or hydrocarbon radicals, and X is a bivalent acyclic or cyclic hydrocarbon radical or a heterocyclic ring system which includes one or both of the nitrogen atoms. cals above referred to may also include .heteroatoms, such as oxygen, sulfur or nitrogen, as well as heteroatom groups derived therefrom Furthermore, the above by.-

drocarbon radicals may also have substituen'ts 'containiug Oxygen, sulfur or nitrogen atoms.

The hydrocarbon radi- Compounds which fulfill this task (24) Diphenylmethane-4,4'

if desired, in the form of their salts formed with in: organic or organic bases. l I Examples of compounds of this type are the followmg:

N,N A) diethyl-ethylenediamino-N,N-bis- (ethanesulfonic 1,3-diaminopropane-2-su1fonic acid N,N,N,N' tetra n-butyl-1,3-diaminopropanol-2-monosulfuric acid ester Piperazine-N,N'-bis-(Z-hydroxypropane-sulfonic acid) 2,5-diaminobenzene-l-sulfonic acid 1 2,5-diaminobenzene1,4-disulfonic acid as well as other sulfonic acid or sulfuric acid ester denvatives of compounds of the described type as fol-. lows:

(1) l:I1,N diethyl ethylenediamine-N'-propane-sulfonic act (2) N,N diethyl-ethylenediamine-N',N-bis-(propanesulfonic acid) (3) N,N diethyl ethylenediamine-N,N'-bis-(propane sulfonic acid) (4) l:,N,N'-triethyl-ethylenediamine-N-propane-sulfonic (5 N- ethyl ethylenedianiine-N,N'N-bis-(propane-Sui:

fonic acid) (6) lgghylenediamine N,N,N',N'-tetra-(propane-sulfonic (7) Ethylenediamine-NN' bis-(propane-sulfonic acid) (8) lgLN' diethanol-ethylenediamine-N-propane-sulfonic aci (9) N,N diethanol-ethylenediamine-N,N-bis-(propanesulfonic acid) (10) N,N,N-triethanol-ethylenediarnine-N'-propaue-sulfonic acid (11) N ethanol ethylenediami-ne N-ethanol-2-sulfuric acid ester 1 (12) N,N,N'-triethanol-ethylenediamine-N-ethanol-2-sul= furic acid ester .(13) d;,3 propylenediamine N,N bis-(butane-sulfonic ac v (14) 1,3-propylenediamine-N-(butane-sulfonic acid) 15) 1,4 tetramethylenediamine N,N,N',N'-tetra- (pro; pane-sulfonic acid) (16) 1,4- tetramethylenediamine N,N bis (isobutane:

sulfonic acid) (17) 1 ,6-heXamethylenediamiue-N,Nbis- (ethane-sulfonie acid) (l8) l,6-hexamethylenediamine-N-propane-sulfonic acid (19) 1,Z-phenylenediamine-N-propane-sulfonic acid I (20) 1,4 phenylenediamine N,N bis-(butane-sulfonic acid) (21) 1,4-naphthylenediamine-N,N' bis-(propanesulfouic acid) (22) Diphenylamine-4-aminopropane-sulfonic acid (23) Diphenylainine 1 4,4 bis (aminopropane-sulfonic acid) "1;; bis (iaminobutane-sulf his acid). g i I i 1". i (25 Diphenylene-4,j4'-bis-(aminopropane sulfonic *acid) (26). Pyridine 2-aminoethane sulfonic acid (27) .Pyridine-4 aminodiethane-su1fopic acid (28)" 2-anilinopyridine-N-propane-sulfonic acid (29) Quinolinei aminobutane-sulfoiiic acid .ii

(30) Quinoline-4-aminodibutanc-sulfonic acid (3 l 3- (3'-sulfopropylamino) -carbazole-9-N-propane-sulfonic acid (32) .3,7-dimethyl-2,6-diarnino-acridine-6-N-propanesulfonic acid (3 3) Piperazine-N-propane-sulfonic acid ('34) 2-methylpiperazine-N-b utane-sulfonic acid (35) 2,5 dimethylpiperazine-N,N-bis(propane-sulfonic acid) (36) N-N'-propane-sulfonic acid 7 (37) PiperazineN,N'-bis-(methanol-sulfuric acid ester) (38) Piperazine-N,N-his-(phenylpsulfonic acid) (39) 2,5-diketopiperazine-N-propane-sulfonic acid (40) N-ethyl-Z,S-diketopiperazine-N'-butane-sulfonic acid (41) Piperazine-N,N'-bis-(benzyl-p sulfonic acid) (42) 1,3 bis (diethylamino) propanol-Z-sulfuric acid ester (43) 1,3 bis (dipropylamino)-propanol-2-sulfuric acid ester (44) 1,3-bis-(diisopropylamino)-propanol-2-sulfuric acid ester (45) 1,3 bis (dimethylamino) -propanol-2-sulfu ric acid ester (46) 1 diethylarnino-3-methyl-dodecyl-amino-propanol- 2-sulfuric acid ester (47) 1 diethylamino-3-dodecylamino-prop-anol-2-sulfuric acid ester (48) 1 methylanilino-3-diethylamino-propanol-2-sulfuric acid ester (49) 1 methylanilino 3 piperidino-propanol-Z-sulfuric acid ester (50) l methylanilino 3-morpholino-propanol-2-sulfuric acid ester (51) 1 cyclohexylamino-3-diethylamino-propanol-2-sulfuric acid ester (52) 1,3-bis-(cyclohcxylamino)-propanol-2-sulfuric acid ester (53) 1 dicyclohexyl amino-3-diethylamino-propanol-2- sulfuric acid ester 54) 1 dicyclohexyl-arnino-3-cyclohexylamino-propanol- 2-sulfuric acid ester (55) 1,3-bis (dicyclohexyl aminoIt-propanol-Z-sulfuric acid ester (56) 1,3 bis (methyl-ethyl-amino) -propauol-2-sulfuric acid ester (57) 1,3-bis-(ethylamino) -propanol-2-sulfuric acid ester 58) 1,3-bis (methylamino) propanol-Z-sulfuric acid ester These compounds are derivatives of the diarnino compounds of our prior application Ser. No. 458,984.

When any of the above compounds or mixtures thereof, containing sulfonic acid, or sulfuric acid ester substituents, are added to electroplating baths containing brightening agents, electrodeposits produced thereby are bright and lustrous despite the fact that the bath contains impurities of the type described above, such as impurities which cause hardness, etc. Such bright deposits are ob tained over the entire effective range of current densities. In addition, these additives have the further advantage that they increase the ductility of the electrodeposits. Furthermore, the above-mentioned additives are entrained with the metal electroplates to a substantially lesser degree than the corresponding compounds vof the principal patent, which results in a much more economical consumption.

The amounts in which the additives in accordance with our invention can be added to produce the desired eifect range from about-0.01 gn1./liter of bath to about 15 gm./ liter of bath, but the preferred amount is from 3 to 12 gnu/liter of bath. The precise amounts required vary from one additive to the other and are also dependent upon the type of brightening agent employed and the amount and kind of inorganic impurities present in the bath. In general, objects can be electroplated in such baths at temperatures ranging from 20 C. to 60 C., and

with current densities ranging from- 0.5 to 15 ampJdm".

The use of the additives in accordance with our invention does not require any change in the composition of the electroplating baths commonly use, nor does it require any change in the conditions under which objects are usually electroplated, particularly with respect to the temperature of the plating bath and the current densities usually employed. In the form of amines the additives we use are soluble in the usual acid metal salt baths, and particularly in copper-plating baths containing the usual copper salts in an acid aqueous solution. The additives are not decomposed during the electroplating-process.

The above-described additives for electroplating baths in accordance with our invention can be used in conjunction with any electroplating bath containing a brightening agent and in which the quality of the metal electrodeposits produced therefrom are adversely afiected by impurities of the type described, such as, for example, in zinc-, chromiurn-, precious metal-, and particularly copperplating baths which contain brightening agents, and in particular sulfonic acid brightening agents.

Brightening agents usable for the process according to the above noted invention are listed in the following table:

(1) N,N diethyl dithioca-rbamic acid n-propylester-wsodium sulfonate (2) N ethyl dithiocarbamic acid n propylester 0:-

sodium sulfonate (3) N methyl dithiocarbamic acid n propylesterw-sodium sulfonate (4) N,N dimethyl dithiocarbamic acid n propylester-w-sodium sulfonate (5) N isopropyl dithiocarbamic acid n propylesterw-sodium sulfonate (6) N,N diisopropyl dithiocarbamic acid n propylester-w-potassium sulfonate (7) N butyl dithiocarhamic acid n propylester orpotassium sulfonate (8) N,N dibutyl dithiocarbamic acid n r propylesterw-sodium sulfonate (9) N octyl dithiocarbamic acid n propylester orsodium sulfonate (l0) N,N dihydroxyethyl dithiocarbamic acid npropylester-w-sodium sulfonate (11) N hydroxyethyl dithiocarbamic acid -n propylester-w-sodium sulfonate (12) N,N pentainethylene dithiocarbamic acid n propylester-w-sodiumsulfonate (13) N piperazino dithioformic acid n propylesterw-sodium sulfonate (14) 2 mercaptobenzthiazole S propan w sodium sulfonate (15) S phenyl trithiocarbonic acid S propane wsodiurn sulfonate (16) Isothiourea S propane w sulfonic acid (17) 5 phenyl 1,3,4 oxdiazolyl 2 mercaptopropane-w-potassium sulfonate (18) 1,3,5 triazine 2,4,6 tris (mercapto n propane-w-sulfonic acid) (19) 1,3,5 triazine 2 mercapto 4,6 bis (mercapto-n-propane-w-sulfonic acid) (20) 1,3,4 thiadiazole 2,5 bis (mercapto propane-w-sulfonic acid) (21) 1,3,4 triazole 2,5 bis (mercapto n propanew-sulfonic acid) (22) 1,3,4 oxadiazole 2,5 dis (mercapto n propane-w-sulfonic acid) (23) N,N piperazino bis (dithioformic acid npropylester-w-sulfonic acid) (24) Dithiohiuret S,S' di n propane w sulfonic acid (25 N,N' methylene di isothioureido S it propane-w-potassium sulfonate (26) N,N' ethylene di isothioureido S n propanew-sodium sulfonate (27) N,N' hexamethylene di isothioureido S npropane-w-sodium sulfonate (28) N,N' phenylene di isothioureido S n propane-w-sodium sulfonate (29) 2,2 (:,{3 ethylenedithio) bis [4,6 bis (mercapto n propane w sulfonic acid) 1,3,5 triazine] (30) 2,2 (12,5 ethylenedithio) bis (mercapton-propyl-w-sulfonic acid)-1,3,4-thiazole] Instead of the -n-propylor -n-propane radical respectively the above named compounds may obtain likewise the following radicals:

(a) -methyl- (b) -ethyl- (c) -butyl- (d) -2-hydroxypropyl.

(e) -2-chlorpropyl- (f) p py (g) y The following examples will enable persons skilled in the art to understand our invention more completely. However, it will be understood that there is no intention on our part of limiting our invention to these examples.

Example I Example 11 When 1.5 gm./liter N,N,N,N' tetra n butyl 1,3- diaminopropanol-2-mono-sulfonic acid ester are added to an acid copper-plating bath containing 250 gm./liter technical-grade copper sulfate, 70 gm./liter concentrated sulfuric acid and 0.3 gm./liter N,N-diethyl-dithiocarbamic acid-ethylester-w-sodium sulfonate, as brightening agent, electroplating of sheet iron preplated in a cyanide bath is provided with a full bright copper electroplate. The best copper electroplates are obtained when the electroplating step is carried out at C. and within a current density range between 1 and 6 amp./dm. .When the sheet iron is electroplated without the addition of 1.5 gm./liter N,N,N.,N'-tetra-'n-butyl-1,3-diaminopropanol-2- mono-sulfuric acid ester, a satisfactory brightening effect is achieved only within a current density range of 2 to 3 amp./dm.

Example 111 sodium sulfonate, as brightening agents, and 1 gm./liter,

ZQS-diarnino-benzene-1,4-disulfonic acid. At temperatures between 20 and 45 C., objects may be electroplated at current densities up to 13 amp./dm. Without the addition of 2,5-diaminobenzene-1,4-disulfonic acid the copper electroplates are much less bright.

6 Examples 1 V-XX V1 In the table some compositions for copper plating baths are listed. The copper baths contain 100-240 gmJliter CuSO .5H O, 20-120 gm./liter concentrated sulfuric acid and the following amounts of brightening agents according to the above noted list and the following amounts of sulfonic acid or sulfuric acid ester derivatives respectively of the diamino compounds free from carboxyl groups according to the above noted list:

preferred diamino preferred brightenconcentrasulfonic concentra- Example No. ing agent tion, acid or tion gin/liter sulfuric gIuJliter acid ester 23 (d) 0. 75 38 l. 0 13(a) 0. 5 18 8.0 29(5) 0. 05 33 8.0 21(1) 0. 1 36 3. 0

12(b) 0. 25 47 O. 5 14(a) 0. 25 54 0. 5 16(b) 1. 5 57 1. 0 5(0) 0.2 51 2.0 23 0.25 55 3. 0

While we have disclosed certain specific embodiments of our invention, it will be understood that we do not intend to be limited thereby and Various changes and modifications may be made without departing from the spirit of the disclosure and the scope of the appended claims.

We claim:

1. In a process of producing bright metal electrodepose its said metal being selected from the group consisting of copper, zinc, chromium and precious metals, from electroplating baths containing impurities found in hard water and in technical grade metal salts, and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gm./liter of an organic amino compound free from carboxyl groups and having the general structural formula Rr Rt wherein X is an organic radical selected from the group consisting of bivalent acyclic hydrocarbon radicals, bivalent cyclic hydrocarbon radicals and heterocyclic hydrocarbon radicals which include at least one of the nitrogen atoms, and R R R and R are radicals selected from the group consisting of hydrogen, substituted hydrocarbon radicals and unsubstituted hydrocarbon radicals, wherein at least one of the radicals selected from the group consisting of R R R R and X is substituted with a substituent selected from the group consisting of sulfonic acid and sulfuric acid ester groups, X being free of said substituent when said substituent is on one of said radicals selected from the group consisting of R R R and R whereby said impurities are prevented from interfering with the production of bright metal electrodeposits.

2. In a process of producing bright metal electrodeposits said metal being selected from the group consisting of copper, Zinc, chromium and precious metals, from electroplating baths containing impurities found in hard water and in technical grade metal salts; and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to -15 gm./liter of an amino compound free from carboxyl groups having the general structural formula wherein X is an organic radical selected from the group consisting of bivalent acyclic'hydrocarbon radicals, bivalent cyclic hydrocarbon radicals, and heterocyclic hydrocarbon radicals which include at least one of the nitrogen atoms, and R R R and R are selected from the group consisting of hydrogen, substituted hydrocarbon radicals and unsubstituted hydrocarbon radicals, wherein at least one of the radicals selected from the group consisting of R R R R and X is substituted with a sulfonic acid group, X being free of said substituent when said substituent is on one of said radicals selected from the group consisting of R R R and R whereby said impurities are prevented from interfering with the production of bright metal electrodeposits.

3. In a process of producing bright metal electrodeposits said metal being selected from the group consisting of copper, zinc, chromium and precious metals, from electroplating baths containing impurities found in hard water and in technical grade metal salts, and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gm./liter of an amino compound free from carboxyl groups havingthe general structural formula wherein X is an organic radical selected from the group consisting of bivalent acyclic hydrocarbon radicals, bivalent cyclic hydrocarbon radicals, and heterocyclic hydrocarbon radicals which include at least one of the nitrogen atoms, and R R R and R are selected from the group consisting of hydrogen, substituted hydrocarbon radicals and unsubstituted hydrocarbon radicals, wherein at least one of the radicals selected from the group consisting of R R R R and X is substituted with a sulfuric acid ester group, X being free of said substituent when said substituent is on one of said radicals selected from the group consisting of R R R and R whereby said impurities are prevented from interfering with the production of bright metal electrodeposits.

4. In a process of producing bright copper electrodeposits from electroplating baths containing impurities found in hard water and in technical grade copper sulfate, and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gm./liter of piperazine-N,N-bis-(Z-hydroxypropane-sulfonic acid) whereby said impurities are prevented from interfering with the production of bright copper electrodeposits.

5. In a process of producing bright copper electrodeposits from electroplating baths containing impurities found in hard water and in technical grade copper sulfate and containing l,3-5-triazine-2,4,6-tris(mercapto-2-hydroxy-propane-sulfonic acid) as a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gm./liter of piperazine-N,N-bis(2-hydroxypropane-sulfonic acid), whereby said impurities are prevented from interfering with the production of bright copper electrodeposits.

6. In a process of producing bright copperelectrodeposits from electroplating baths containing impurities found in hard water and technical grade copper sulfate, and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gut/liter of N,N,N'N'-tetra-n-butyl-1,3-diaminopropanol- 8 Z-mOno-suifuricacid ester, whereby said impurities are prevented from interfering with the production of bright copper electrodeposits.

7. In a process of producing bright copper electrodeposits from electroplating baths containing impurities found in hard water and technical grade copper sulfate and containing N,N-diethyl-rithiocarbamic acid-ethylester-w-sodium sulfonate as a brightening agent, the step which comprises adding 0.01 to 15 gm.-/liter of N, N,N"N'- tetra-n-b'utyl-1,3-diaminopropanol-2-monosulfuric acid ester to such electroplating baths, whereby said impurities are prevented from interfering with the production .of bright copper electrodeposits.

8. In a process of producing bright copper electrodeposits from electroplating baths containing impurities found in hard water and technical grade copper sulfate, and containing a brightening agent, the step which com-. prises adding to such electroplating baths 0.01 to 15 gm./liter of 2,5-diaminobenzene-1,4-disulfonic acid, whereby said impurities are prevented from interfering with the production of bright copper electrodeposits.

9. In a process of producing bright copper electrodeposits from an electroplating bath containing impurities found in hard water and in technical grade copper sulfate and containing a mixture of l,3,5-triazine-2,4,6-tris- (mercaptoQ-hydroxypropane sulfonic acid and N,N-di-' ethyl-dithiocarbamic acid-ethylester-w-sodium sulfonate as brightening agents, the step which comprises adding to such electroplating bath 0.01 to 15 gm./liter of 2,5-diaminobenzene-l,4-disulfonic acid, whereby said impurities are prevented from interfering with the production of bright copper electrode'posits.

10. In an acid copper electroplating bath comprising technical grade copper salts and hard tap water, the improvement which comprises a component for rendering impurities in said bath harmless, comprising 0.01 to 15 gm./liter of an organic amino compound free from carboxyl groups having the general structural formula wherein X is an organic radical selectedfrom the group consisting of bivalent acyclic hydrocarbon radicais, bivalent cyclic hydrocarbon radicals and heterocyclic hydrocarbon radicals which include at least one of the nitrogen atoms, and R R R and R are radicals selected from the group consisting of hydrogen, substituted hydrocarbon radicals and unsubstituted hydrocarbon radicals, wherein at least one of the radicals selected from the group consisting of R R R R and X is substituted with a substituent selected from the group consisting of sulfonic and sulfuric acid ester groups, X being free of said substituent when said substituent is on one of said radicals selected from the group consisting of R R R and R whereby said impurities are prevented from interfering with the production of bright metal electrodeposits.

11. In a process of producing bright copper electro= deposits from electroplating baths containing impurities found in hard water and in technical grade copper sulfate, and containing a brightening agent, the step which comprises adding to such electroplating baths 0.01 to 15 gm. liter of N,N.- diethy1-ethylenediamino-N ,N'-bis-(ethane-sulfonic acid) whereby said impurities are prevented from interfering with the production of bright copper electrodeposits.

References Cited in the fileof this patent UNITED STATES PATENTS 2,837,472 Gundel ,et a1 June 3, 1958 2,849,351 Gundel et a1. Aug. 26, 1958 FOREIGN PATENTS p 1,118,019 France Mar. 5', 1956 Patent No. 2,986,498 May 30, 1961 Wennemar Strauss et al3 It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 5 line 15, for "-n-propane" read n-pr0pane- 1 column 8 line 7 for "rithiocarbamic" read dithiocarbamic Signed and sealed this 21st day of November 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

1. IN A PROCESS OF PRODUCING BRIGHT METAL ELECTRODEPOSITS SAID METAL BEIGN SELECTED FROM THE GROUP CONSISTING OF COOPER, ZINC, CHROMIUM AND PRECIOUS METALS, FROM ELECTROPLATING BATHS CONTAINING IMPURITIES FOUND IN HARD WATER AND IN TECHNICAL GRADE METAL SALTS, AND CONTAINING A BRIGHTENING AGENT, THE STEP WHICH COMPRISES ADDING TO SUCH ELECTROPLATING BATHS 0.01 TO 15 GM./LITER OF AN ORGANIC AMINO COMPOUND FREE FROM CARBOXYL GROUPS AND HAVING THE GENERAL STRUCTURAL FORMULA 